Printing sleeves are removable from the rolls by various known means, some employing air under pressure (see U.S. Pat. No. 3,146,709) and others radial expansion upon axial contraction (see U.S. Pat. No. 2,450,727). In particular there has recently been proposed, in U.S.A. co-pending patent application Ser. No. 755,157 the use of rolls where the core is of different diameters at its two ends, with a corresponding difference on the interior of the sleeve, with air pressure vents from the core.
The use of such sleeves opens up the need for a printing machine in which the sleeve removal can be carried out in situ on the machine itself.
When a new image is to be printed a new sleeve is provided and in the past this has meant the removal of the complete roller from the printing machine and its subsequent replacement after the sleeve has been changed. It is further necessary to re-adjust the contact pressures between the sleeve and the impression cylinder and the sleeve and the inking roller. All of these operations are costly, both in terms of labour charges and of unproductive or downtime of the printing machine.